Komatsu ecot3 PC300LC-8 Shop Manual page 377

30 Testing and adjusting
Adjustment
a Adjustment of the unload valve is not available.
1. Adjustment of main relief pressure
a When the relief pressure of the work equip-
ment circuit or travel circuit is abnormal, ad-
just main relief valves (3) and (4) according to
the following procedure.
q (3): For the front pump circuit
q (4): For the rear pump circuit
a As for the main relief valve, be sure to adjust
its low-pressure relief pressure alone (adjust-
ing the low-pressure relief pressure automat-
ically sets the high-pressure relief pressure,
too.).
a When the low-pressure relief pressure is
turned on, the 2-stage relief valve is OFF and
thus the pilot pressure is not applicable to the
switching port.
1) Disconnect the pilot hose.
2) Loosen locknut (5) and turn holder (6) to
adjust the relief pressure.
a Turning the holder clockwise increases
the pressure. Turning it counterclockwise
decreases the pressure.
a Quantity of adjustment per turn of holder:
Approx.20.5 MPa {Approx.209 kg/cm
3
Locknut:
PC300, 350-8
49.0 - 58.8 Nm {5 - 6 kgm}
3) Check the pressure again after the adjust-
ment, following the aforementioned steps for
measurement.
a Connect the pilot hose when measuring
the oil pressure.
2. Adjustment of boom LOWER relief pressure
(on the side where high pressure is set)
a When the high-pressure relief pressure for
the boom LOWER is not normal, adjust the
high pressure side of the safety and suction
valve (7) for the boom LOWER in the follow-
ing procedure.
a The high-pressure relief pressure mode de-
notes the state in which the machine push-up
switch is turned on, disabling to apply the pi-
lot pressure to the switching port.
1) Disconnect the pilot hose.
2) Loosen locknut (8) and turn holder (9) to
adjust the relief pressure.
a Turning the holder clockwise increases
the pressure. Turning it counterclockwise
decreases the pressure.
a Pressure adjustable from a single turn of
the holder:
Approx. 21.8 MPa {Approx.222 kg/cm
3
2
}
Locknut:
SEN02625-06
93 - 123 Nm {9.5 - 12.5 kgm}
2
}
37